In the absence of sufficient data for nearly all economies until well into the 19th century, past GDP per capita cannot be calculated, but only roughly estimated. A key notion in the whole process is that of subsistence, the income level which is necessary for sustaining one's life. Since pre-modern societies, by modern standards, were characterized by a very low degree of urbanization and a large majority of people working in the agricultural sector, economic historians prefer to express income in cereal units. To achieve comparability over space and time, these numbers are then converted into monetary units such as International Dollars, a step which leaves a relatively wide margin of interpretation.

The following estimates are taken exclusively from the 2007 monograph Contours of the World Economy, 1–2030 AD by the British economist Angus Maddison.[1] For his separate estimate of Roman GDP (PPP) per capita and that of other authors, see below.

The Maddison project is an international group of scholars who continue and build upon Maddison's work. In their 2014 report they concentrate on the pre-1820 period. Their revised figures show pre-industrial Europe to be richer, but its economic growth to be slower than previously thought.[2] Their findings confirm Maddison's view that the income gap to Asia was already large before the Industrial Revolution.[3] The entirety of their GDP per capita estimates can be obtained from their online database.[4] The following data selection they present in their published paper:[5]

The following estimates were made by the economic historian Paul Bairoch.[6] Unlike other estimates on this page, the GNP (PPP) per capita is given here in 1960 US dollars. Unlike Maddison, Bairoch allows for the fluctuation of borders, basing his estimates mostly on the historical boundaries at the given points in time.[7]

The following estimates are taken from a revision of Angus Maddison's numbers for Western Europe by the Italian economists Elio Lo Cascio and Paolo Malanima.[8] According to their calculations, the basic level of European GDP (PPP) per capita was historically higher, but its increase was less pronounced.

Much of the recent work in estimating past GDP per capita has been done in the study of the Roman economy, following the pioneering studies by Keith Hopkins (1980) and Raymond Goldsmith (1984).[9] The estimates by Peter Temin, Angus Maddison, Branko Milanovic and Peter Fibiger Bang follow the basic method established by Goldsmith, varying mainly only in their set of initial numbers; these are then stepped up to estimations of the expenditure checked by those on the income side. Walter Scheidel/Steven Friesen determine GDP per capita on the relationship between certain significant economic indicators which were historically found to be plausible; two independent control assumptions provide the upper and lower limit of the probable size of the Roman GDP per capita.[10]

Italia is considered the richest region, due to tax transfers from the provinces and the concentration of elite income in the heartland; its GDP per capita is estimated at having been around 40%[18] to 66%[19] higher than in the rest of the empire.

The GDP per capita of the Byzantine Empire, the continuation of the Roman Empire in the east, has been estimated by the World Bank economist Branko Milanovic to range between $680 and 770 (in 1990 International Dollars) at its peak around 1000 AD, the reign of Basil II.[20] This is 1.7 times the subsistence level as compared to the slightly higher value of 2.1 for the Roman Empire under Augustus (30 BC–14 AD).[21]

^Bolt, Van Zanden 2014, p. 635, table 1; 637, table 2. Anatolia is present-day Turkey, forming part of the Byzantine and then Ottoman Empires. 1348 Japanese GDP per capita is actually for the year 1280, 1600 US figure for 1650 and 1800 Anatolian value for 1820.

^ abcThe border between "Western Europe" and "Eastern Europe" as defined by Bairoch corresponds to the iron curtain, with "Eastern Europe" being identical to the Eastern Bloc (Bulgaria, Czechoslovakia, the German Democratic Republic, Hungary, Romania, Poland, and the USSR plus Albania). All the rest of Europe makes up "Western Europe" (Bairoch 1976, pp. 317, 319).

^Milanovic 2006, p. 459. This latter value also forms the basis for the only superficially lower $633 given by Milanovic et al. 2007 in the table above. The difference in the Roman and Byzantine GDP (PPP) per capita is due to the authors operating with differing conversion rates for the subsistence level: $300 in the Roman case (2.1 x $300 = ~$633), $400 in the Byzantine one (1.7 x $400 = $680). This means that Roman GDP (PPP) per capita was around 20% higher than the Byzantine one.